C clamp



Jan. 2, 1945. H `F HUSTED 2,366,263

G CLAMP Filed April 6, w1942 Patented` Jan. 2, 1945 .UNITED l STATE PATENT OFFICE f This invention relates to clamps of the C type.

An object of this invention is to provide a `C clamp which is so constructed that in the use thereof by a workman it will not` be possible for the workman to tighten the clamp to a point` where the` clamp will break. I

`Another object of this invention is to provide in combination with a C` clamp, a safety means which will `permit the workman to tighten the` clamp to a degree slightly less than the break--` ing strain of the clamp, but if additional pres--` sure is `attempted the safety head will be effective to prevent application of` such additional` pressure without releasing the maximum pres-` sure permitted by the lsafety means.

` In the use of conventional C clamps by a workmaniit frequently happens that atool, such as a `wrench or thelike, is applied to the wingsor head of the `adjustable jaw,` with the result that the clamp is placed under excessive pressure strains which resultin twisting of the clamp, distortion or spreading of the clamp jaws, or

" 3-3 f Figure 2.

" ty device mounted on the upper end movable jawshaft. I

Figure 1 is a detail side elevation, partly in section, of a C clamp `constrl'icted accordingto an embodiment of this invention. I Figure 2 is a fragmentary top plan of the safe` of the Figure 3 is a sectional view taken on the line Figure 4 is a sectional view of the keeper embodied in this invention;

Figure 5 is a fragmentary vertical section of the locking bolt embodied with the movable jaw cracking and breaking or spreading of the clamp.

This results from the `use of a light or small clamp fora job not intended for the particular clamp, `and inradditionto ruininga clamp the Workman loses valuable.. time in `obtaining a clampsuitable for the jobk AIt is, therefore,` an object of this invention to` provide a C` clamp which is so constructedth'at the workman cannot break the" clamp orotherwise ruinthe same by h applying a tool thereto inorder to clamp the articles under the degired pressure.

n A further object of this invention is to pro` vide asafety device in a: clamp whichiissimple` in construction so that it may be made at low` cost andwill withstand the necessary pressure strains without damage thereto or tothe clamp. `A further object of this invention is to provide a safety device of this kind which Will release the clamping screw from .application of a predetermined maximum pressure but which will permit ready reverse turning `of the.` clamping screw toward releasedposition. Y To the foregoing objects and to others :which mayhereinafter appear, the invention consists of the novel construction, combination' and ar-` rangement of parts as `will be more specifically referred to and illustrated in the `accompanying drawing wherein are shown embodiments of the I invention, but it is to beunder'stood tha-tchanges,

variations, andmo'dications may be resorted to which fall within the scope of the invention as I shaft. I I Y i Figure 6 is a fragmentary side elevation of an improved form of safety device. 1

Figure '7 is a fragmentary side elevation of a further modification of this invention.

Figure 8 is a plan view of the keeper plate einbodied` in the form of the invention shown in l Figure 7. Referring to "ignates generally a C-shapedframe structure in cluding `a vertically disposed framemember II, a lower right angular framemember I2 and an upper right angular frame member I3 disposed in parallel relation with the lower frame mem-` ber I2. The lower frame member I2 has formed integral with the forward end thereof, a. station-` ary or fixed jaw member I4. The upper frame member I3 `has formed integral therewith a threaded boss I5 through which a threaded shaft I6 engages. The shaft I6 at its lowerend, has svvivelly or rotatably mounted thereon, amovable jaw Il whichconfrontsa stationary jaw I4.

In order to providemeans `whereby the tension applied to the frame I0 by clamping of an article between the two `jaws I4 and `Il may be prevented beyond a predetermined point, which point is slightly less than the breaking strain of the frame Ill, I have provided `a safety means, to l be hereinafter described, which is mounted on `theupp'er end `of the threaded shaft I6. The shaft I6, at its ,upper end, `is formed `with a" smooth reduced stud I8 which forms a shoulder I9 `at the upper end of the threaded portion vof the shaft I6. A lower washer or annular member 2B is mounted on the stud or shaft extension I Y I8 and rests against the shoulder I9, being tight- 1y pressed on the stud or shaft extension I8 so that the washer 20 will thereby loe held against rotation relative to the extension I8. A substantially rectangularly shaped block 2I is loosely mounted onthe stud I8 and is formed with a` I 'transversely extending opening 22gthrough which y"5&5

"an operating` bar 23 slidably engages so that the the drawing theV numeral ID des- I,

.and separating the upper side into two faces 26 and 21. The faces 26 and 21 are cam faces which taper in the axial direction of said groove but their inclination is in the opposite sense. A locking pin 29 is mounted transversely through side ofthe block 31. The lower side of the block 31 may be formed with an annular series of serrations 48 and the upper side of the washer 45 may also be formed with an annular series of serrations 49 so thatv the sblock 31 will be provided with suicient resistance tending to hold this block 31 against rotation relative to the shaft 39. However, when undue strain is applied to the block 31 and the shaft 39, the spring washer will be slightly compressed by the locking member 44 moving out of the keeper groove 43 and slidably engaging the oppositely inclined l faces 4|.and 42. f

the upper end portion of the stud I8 projecting laterally thereof and engaging within the groove 28. The pin 29 is formed intermediate the ends thereof with an annular groove 30 and preferably the upper end of the stud I8 is providedwith a dent 3| pressing aportion .of the metal of the stud "I8 into thegroove 36\.in.order to thereby hold the pin 29 `against endwise movement.

Intorder .to provide a means whereby the keeper '25 may beheld in engagement with the pin or locking bolt 29 I have provided asplit resilient washer or ring 32 which engages against the washer 20. A washer 33l is interposed between adapted .to engage.

the upper side of the spring ring 32 and the lower side of the block '210, tand is formed -in its lowerface with serrations v34 so as to thereby hold the washer 3,3 against rotation relative to the spring 32. The provision of the oppositely inclined faces 26 and 21 provides oppositely disposed locking andreleasing shoulders.' 35 and `36 respectively so that when the operator 23 is rotated and thelshaft |6 rotatedtherewith, the low shoulder 36, upon application of an undue strain on the frame lil, will permit the locking pin 29 to be released from the keeper groove 28 when the shaft |6 is rotated in a clockwise or tightening direction. i The provision of the high shoulders 35. opposite to the -low'shoulders 3.6, provides .a means whereby the shaft |16 may subsequently be `rotated in a counterclockwise or released vdirection 4to thereby release `the `material .engaging between the two jaws |4 and l1.

- "Referring now vto Figure 6, there' is disclosed a slightly modied form of this invention wherein -a block r31 is rotatably mounted on the rel `duced studl 38 .of the threaded movable jaw car.- rying shaft 36. AThe block 31 is formed with a transversely extending opening 49 through which ahandle vor voperator may slidab-ly engage. The block 31 is formed on the upper side thereof with oppositely inclined keeper surfaces 4| and 42 which are separated by a transversely extending. keeper vgroove 43. A lockingpin 44, similar to the pin 29, is mounted in the stud 38 andr normally engages within the keeper'groove 43. T'he inclined faces 4| and 42 are similar in every detail to the inclined faces 26 and 2,1. In the present instance, however, the block 31 is hardened to :the desired degree whereas in the previous ,modification the keeper plate 25 is hardened or suitably tempered so that the locking pin 29 will rnotinjure the upper surface of the keeper plate Y25. `A washer 45 is mounted on the stud 3.8 and ,engages against the shoulder 4G formed between the lower end of the stud 38 and the upper end of the threaded shaft 39. l The block 31 is spring Ipressed forv engagement of the locking member ,44 in the keeper groove 43 by means of an any nular spring washer 41 `.which is interposed between ithe stationary Washer 45 and the lower,-

Referring now to Figures 7 and 8 there is disclosed a further modification of this invention which embodies a threaded shaft 50 similar to the shaftf |6 and which is formed with an un-y vthreaded upper end portion 5|.

An annular ange or shoulder 52 is formed integral with the shaft '50 and the extension 5|r and provides a shoulder against which .a lower washer I5.3 is .An 4annular 4operator 54 is rotatably mounted on ,the extension 5|, and iS formed with a pair ofv diametrically opposed Wings 5.5.` An annular keeper plate 56 is mounted on the shaft extension l51| ,and yis formed with 0D- positely .inclined `faces 51 and 5&3.-` The keeper member 5b4 is also formed with a keeper-groove' .5B within which a 1ockingbo1t6|Lsimilar tothe bolt or vpin 29, is .adapted to lnormally engage, i .The `keeper member .5B is also formed with a downwardlyy extending part el, Which-engages f ih et diaimetrically disposed groove 62 formed in the upper sideo :the head or body, .54 so that the keeper member 5,6 will be held against rotation relative to the body or Ahead 54. The keeper member 561s ,formed of highlyy tempered material and hardened to the desired degree so :that `this keepermember will .not be injured `during the use of, the clamp. The keeper member l 55 is held :nesilently vin engagement with the bolt x60 by means of a split resilient ring or washer` 63 which is interposed between l.the lower washer ,53 and` the upper washer 64 engaging against the lower side ofthe body ,for headx54. In the use and opera-.tion `of this safety clamp the desired article. or articles are interposed .between-:the Atwo jaws |4 and l1. The movable jaw :I1 ,may be tightened to the desired degree by rotating the shaft lr6 through the `medium of the 4operator 23. Normally, the :bolt or lock'- ing member 2:9 :will be positioned within the groove 28 of the keeper plate 25 but when undue pressure has .been applied to the frame ill), by tightening of theI movable jaw l1, the bo1t-29 ride out ofv the .keeper groove 2=8 and yygilaoe :thespring member 32 under additional tension. In this manner, the shaft |16 will be stationary whereas :the block 2| will be rotated with ,the operator .23 about .the stud 18. In .order to `loosen theA movable jaw `|1 ,it ,is only necessarytto reverse :the rotation vof the 4block 2i and .at ythis time the pin .or bolt 2:9 will engage the high portions 35 of the keeper :member 25 thereby limiting the reverse rotation of Vitlflewblock 2| ywith respect :to .the stud lil.` By mounting .the locking der to rotate the block 2|, additional strain applied to the frame l0 -by the tool will not break or bend the frame .|IJ, due to the` release of the .block 2l from the shaft I6 after a substantially breaking strain has beenapplied to the frame l0.

`This safety clamp is of simple construction so that it can be manufactured and produced at t low cost and will effect a verymateral saving in tools used in a shop,\as the safety device `will t eliminate any breakin-g `of the clamp on the part of the workmanl What I claim is:

In a clamp, a frame, including a stationary jaw, a threaded shaft in said frame, a movable `jaw carried by one end of said shaft, and an operator slidably mounted on said shaft for rotating the same, means whereby said operator may be released from said shaft for rotation theret about when said movable jaw has been placed under predeterminedpressure, said means comprising an annular plate slida-bly mounted on said shaft, cooperating means on said plate and on said operator for releasably` but non-rotatably t connecting said plate to the top of said operator,

said plate having on the upper,'or free, side` thereof an upwardly opening groove extending `shoulder on said shaft and the other end bear-` ing against the bottom of said operator whereby to normally hold the projecting ends of said pin in the groove of said plate until a predeterlmined pressure lbetween said movable and stationary jaws has been reached, further pressure applied tothe operator in the clamping direction effecting the unseating of the ends of said pin from said groove and the rotation of said'plate and operator relative to said shaft with the ends of said pin slidingup said sloping faces, while rotation of the operator in the cla-mp releasing -direction causingsaid shoulders to` abut against the ends of said pin, thereby to turn the shaft to release the movable jaw of the clamp. t

` HARRY F. HUSTED. 

